The present invention relates to a pipette gun and holster assembly which can be mounted on a vertical surface above or proximate a horizontal work table.
On an average day, a pipette gun may be used to meter hundreds of fluid samples. Inevitability, while using the pipette gun, a laboratory technician will be interrupted for a variety of reasons and must suspend use of the pipette gun. If the pipette gun assembly is set down on a table top, the pipette may become contaminated if it contacts the table top. Further, the sample fluid contained in the pipette may run out of the pipette if the pipette gun is set down flat on its side on the table top. Therefore, it would be desirable to provide a stand in which the pipette gun and pipette can be parked while not in use and which prevents contamination of the pipette or spillage of fluid from the pipette when the pipette gun is parked in the stand.
U.S. Pat. No. 5,616,871 (Kenney ""871), incorporated herein by reference, describes a pipette stand which supports the pipette gun and pipette in an upright position on a table top so that the pipette does not contact the table top and so that any liquid in the pipette does not spill out of the pipette or flow back up through the pipette into the pipette gun. The pipette stand disclosed in Kenney ""871 is only useful, however, if there is available space on the table top on which the pipette stand may be rested. Too often the table top is overly crowded with scientific apparatus. Therefore, it would be desirable to provide a pipette gun stand which can be mounted on the unobstructed vertical walls surrounding or proximate the table top.
In many laboratories, a pipette gun is used continuously for several hours by a technician. Over time, the weight of the pipette gun causes fatigue to the technician. For example, a pipette gun having an internal air pressure source may weigh up to 12 ounces. Prior art pipette guns having a remote, external air pressure source are lighter and reduce fatigue. However, the elastomeric tubing connecting the remote air source to the pipette gun is cumbersome and often interferes with the work area. Therefore, it would be desirable to provide a pipette gun having a remote air source and an elastomeric tubing design which does not interfere with the work area.
In order to deactivate the remote, external air pressure source for a short period of time while the pipette gun is not in use, the source must be switched off manually by either unplugging the air pressure source or flipping an external switch on the air pressure source. Because it is inconvenient to repeatedly turn the air pressure source off and on, technicians typically leave the air pressure source activated even while the pipette gun is not in use. Continuously running the remote air source greatly shortens its life-span. Therefore, it would be desirable to provide a pipette gun having a remote air source which is automatically activated and inactivated when the pipette gun is removed from and inserted into, respectively, the pipette gun holder so that the life-span of the remote air pressure source can be extended.
The present invention provides a pipette gun and holster apparatus having an external source of air pressure. The holster can be mounted on the unobstructed vertical walls surrounding or proximate the table top. The pipette gun and pipette can be parked in the holster while not in use, thereby preventing contamination of the pipette or spillage of fluid from the pipette when the gun is parked in the holster.
The remote air source is connected to the pipette gun with a recoiling, elastomeric tubing which does not interfere with the work area. In one embodiment, the remote air source is automatically activated and inactivated when the pipette gun is removed from and inserted into, respectively, the holster so that the life-span of the remote air pressure source is extended.
The apparatus of the invention generally comprises a pipette gun having a remote source of positive and negative air pressure, and a gun holster. The holster is constructed and arranged to support the gun above a work table with the pipette connector oriented generally, vertically downwardly.
The pipette gun has an external, flexible conduit connecting the gun to the remote air pressure source. The pipette gun housing has a hand grip portion and a barrel portion oriented transverse to the hand grip portion. A pipette connector is fixed to and oriented transverse to the barrel portion. An internal conduit is connected to the external flexible conduit and the pipette connector. A valve is located intermediate the internal conduit and is constructed and arranged to selectively regulate the flow of either positive air pressure or negative air pressure through the internal conduit to the pipette connector. A positive air flow trigger and a negative air flow trigger are connected to the valve.
The holster has a base and means for fastening the base to a vertical wall. A mounting bracket is fixed to and extends transverse to the base. The bracket has a bottomless socket constructed and arranged to receive and removably hold the gun by inserting the pipette connector into the socket. The base is removably attached to a vertical surface by suction cups, velcro tabs, magnets, or other releasable fasteners.
The external conduit comprises two-channel plastic tubing having a recoiling portion. One end of the recoiling portion is connected to the gun and the other end of the recoiling portion is connected to the base. The external conduit also has a non-recoiling portion extending from the base to the air pressure source. A male prong connector is fixed to the base for removably joining the recoiling portion and non-recoiling portion of the external conduit.
In one embodiment, the mounting bracket comprises a pair of forks having a base end and a plurality of prongs. The base end of the forks is fixed to the holster base at vertically-spaced locations.
The socket is circular and is formed in between the prongs of each of the forks. The socket has a diameter DS larger than the distance between the prongs DP of the forks.
The pipette connector may have a constant outer diameter DC which is less than DS but greater than DP. In this embodiment, the diameter of the socket DS is greater than DC and the distance between the prongs DP is less than DC.
In another embodiment of the invention, the pipette connector has a frusto-conical shape and having a maximum outer diameter DC1 and a minimum outer diameter DC2. In this embodiment, the diameter of the socket DS1 and the distance between the prongs DP1 of the first fork is greater than the diameter of the socket DS2 and the distance between the prongs DP2 of the second fork, respectively. In this embodiment, DC1 is greater than DP1, DP2 and DS2 but less than DS1. DC2 is greater than DP2 but less than DS1, DP1 and DS2.
In one embodiment of the invention, the remote air pressure source is fixed to the base. A first switch is located proximate the socket. The switch regulates the flow of power to the remote air source. The first switch deactivates the remote air source when the pipette gun is parked in the holster. The switch also energizes the remote air source when the gun is removed from the holster. The apparatus may also include a second switch which deactivates the remote air source independent of the first switch.
A mounting pad removably fixes the external air pressure source to either a vertical or horizontal surface. The mounting pad has a layer of vibration-absorbent material, means for permanently fixing the pad to either a vertical or horizontal surface, and means for removably fixing the remote air pressure source to the pad. In one embodiment, the permanent fixing means comprises a layer of adhesive and the removable fixing means comprises Velcro tab fasteners. The mounting pad may also have a plurality of bores arranged to align with the feet on the remote air source.
The present invention also provides a method of metering fluid using a pipette gun. A pipette gun having a remote air pressure source and holster assembly are provided. The holster is removably fastened to a vertical surface. The pipette gun is supported above a work table with said pipette connector oriented generally, vertically downwardly by parking the pipette gun in the holster. The pipette gun is removed from the holster and fluid is metered with the gun. The external air pressure source is automatically inactivated when the pipette gun is parked in the holster and automatically activated when the pipette gun is removed from the holster.